[TEC] Depth Charge values examined in S3D

[tater]

DCs have a zon file which determines their damage, and a sim file which determines a few other aspects of them in game.

Sim values are:

fall_speed = 3
detonate depth = 25
depth precision = 5

Then stuff related to the shaking of explosions (not damage) and the visual effects.

Fall speed is in m/s I think (and is too high, but dropping it increases chances of sinking the ASW ship)

Depth precision is the error (in meters) of drops made (presumably the error varies based upon crew skill?)

Detonate depth... wtf is it? the _X DCs (thrown) are set to depth 2500. Is that the max depth they fall to?

25 is actually more shallow (in meters) than jap DCs could really be set, even early in the war, and they do seem to drop much deeper. Is the value unused?

tater

[tater]

I changed the detonate depth to 1, no change that I could observe.

Hmmm, I wonder if it has to do with the depth SETTINGS. meaning I should try setting it to 30, with a precision of 1, then set my depth to 45m, and see if they only explode at 30 +-1 or 60 +-1.

tater

[tater]

That doesn't seem to work, either.

Seeing as I was trying to get DCed, and I watched with external camera, I noticed that DCs are non-interactive. Meaning they can (and did) actually detonate inside my hull. Perhaps I need to make the same changes to dc x h as well. I notice that dat has a model, and the regular one does not.

That got me thinking.

I wonder if we could add a collisionable node tothe DCs. Meaning that they would hit the hull and bounce off. They'd still detonate when they were supposed to, but imagine the feeling of being DCed, hearing "Splash! Splash! Splash!" then "boom. BOOM. Klunk, scape... BOOOM!"

hehehe

[GerritJ9]

If fall speed is in m/sec and is too high, reducing the sinkage rate would actually give a ship MORE time to get away before the charge reaches its detonation depth.
Not sure what detonation settings were available to IJN depth charges, but "O.20" was attacked in fairly shallow water off Kota Bharu in December 1941 and tried to escape by creeping away just above the bottom at about 42 metres. Depth charges exploded well above her (about 30m)- apparently the next setting would have meant the depth charges hitting the bottom before they could be set off so it would seem that, at least in 1941/early 1942, the settings available to the IJN were widely spaced, perhaps in the order of 30-60-90 metres?

[mrbeast]

That doesn't seem to work, either.

Seeing as I was trying to get DCed, and I watched with external camera, I noticed that DCs are non-interactive. Meaning they can (and did) actually detonate inside my hull. Perhaps I need to make the same changes to dc x h as well. I notice that dat has a model, and the regular one does not.

That got me thinking.

I wonder if we could add a collisionable node tothe DCs. Meaning that they would hit the hull and bounce off. They'd still detonate when they were supposed to, but imagine the feeling of being DCed, hearing "Splash! Splash! Splash!" then "boom. BOOM. Klunk, scape... BOOOM!"

hehehe

I read about the happening somewhere can't remember where though, the crew could hear the DCs rolling down the side of the conning tower! I also recall an instance where a sub or U boat surfaced and had a dud DC caught on the deck casing! How about opening the hatch and seeing that little baby sitting there?! :o

[tater]

Yeah, from what I've read it was 30, 60, and (later in the war) 90m.

I know the slower sink rate SHOULD work as you suggest, but I thought redwine said he tested as part of die slowly, and they were blowing themselves up. I may be wrong about that, I thought I read it, and I haven't had time to test. Perhaps he made a larger depth error.

tater

[Redwine]

Yeah, from what I've read it was 30, 60, and (later in the war) 90m.

I know the slower sink rate SHOULD work as you suggest, but I thought redwine said he tested as part of die slowly, and they were blowing themselves up. I may be wrong about that, I thought I read it, and I haven't had time to test. Perhaps he made a larger depth error.

tater

Nop... Tater... i think so the DDs blowing up them selves was caused by a conjuction of two thing... the first, may be the depth error, if you put a big depth error, and the DD launch a depth charge with shallow setting.... in example, 15m ....and the error is 15m, it can explodes just at surface causing damage to the DDs.

But after many test i note this happens when the DDs launch a shallow setting, and plus... he is stopped by some reason, in example to avoid colision with another ship....

What can i say about this... may be real... if a DD launch a depth charges at shalow depth, and do not move away from the launching point, it may cause damage.

In the last test of Die Slowly (Stage 22) i have reduced the previous depth errors.... i cant remember what is the value i am using now, but i reduceed it. At prsent i have not DDs taking damage by themselves.

Using a large depth error, it seems to not be exactly an "error" it seems to work as an "depth spread" value.

It is not bad... for the DD, because if you attempt to evade it changing depth at last moment. the big depth error introduce a spread capability, and depth charges explodes at many diferent depths...

Any way, the Dds taking damage by them selves limits this option, i reach a good valur at ... (not sure now) may be 25m.

Fall spees are a chice, but the DDs calculates the impact point with the new fall speed setting, any way it gives you a more small chance to maneuver away, but only if you are too depth.

Detonate depth... i am not sure if it works, but seems to be the air launched depth charges detonation depth....

Hope some of this can help.... :up::up::up::up:

[tater]

I had a feeling I remembered wrong, I was gonna check, but I couldn;t remember which die slowly thread it was in.

As for the detonation depth, that's interesting. Wonder why it is set so differently for the 2 types.

Wait, I just opened Bombs.sim. The air dropped DC is already there, and the detonation depth is set to 5.

Are you saying the value is for a bomb DC, but it's included in all the DCs anyway... wonder how they know.

I was thinking (related to a discussion regarding AI) that making the DCs more historical tied to tougher AI (better sensors) might do the trick. If you could actually set the max detonation depth, then it seems like you could make a new DC for late war, and have a 60m version, and a 90m version.

tater

[tater]

BTW, I think the DC_X_H is the hedgehog, right?

The RL Type 95 had a 100kg warhead, 2 depth settings (30 and 60m), then a 3d setting in late versions (90m). It had a sinke rate of 1.9. Interestingly, they also shipped parachuted versions---not dropped from planes, but a chute to slow the sink rate farther for slower ships to drop them at shallow settings.

This makes me want to mod in some new DCs. Make an early war in 2 versions, one with -1.9 sink, and one even slower for various ersatz ASW assets.

They Type 2 came into service in 1943, and had the sink rate we see in SH4, -3m/s. Some were ~100kg, others 162kg warheads. Looks like it could be set to finer depth control (~25 ft intervals)

They also armed ships (even merchants) with ASW mortars. I wonder if we could mod a hedgehog that fired a single round instead of a pattern...

tater

[Lagger123987]

BTW, I think the DC_X_H is the hedgehog, right?

tater

Right

[skwasjer]

This is the definition of the amun_DepthCharge controller/structure, in the new S3D version (taken from SHSim.act). :up:


/// <summary>
/// The under water falling speed [m/s].
/// </summary>
public float fall_speed;
/// <summary>
/// The detonation depth [m].
/// </summary>
public float detonate_depth;
/// <summary>
/// The depth sensor precision [m].
/// </summary>
public float depth_precision;
/// <summary>
/// The explosion range [m].
/// </summary>
public float explosion_range;
/// <summary>
/// The explosion impulse [t*m/s].
/// </summary>
public float explosion_impulse;
/// <summary>
/// Water hit splash effect.
/// </summary>
public ulong splash;
/// <summary>
/// Water bubbles effect.
/// </summary>
public ulong bubbles;
/// <summary>
/// Water column explosion effect.
/// </summary>
public ulong water_explosion;
/// <summary>
/// Under water explosion effect.
/// </summary>
public ulong under_explosion;
/// <summary>
/// Above water explosion effect.
/// </summary>
public ulong above_explosion;

[Redwine]

I had a feeling I remembered wrong, I was gonna check, but I couldn;t remember which die slowly thread it was in.

tater

Is true into early versions, i am talking about Stage 22... (stage 16 was the last public release) the problem is still present, but not happens often and do not destroy the DDs, the main problem is, when you are at peri depth, and a DD is passing over you and launching depth charges and... at same time it is being stoped by another ships, to avoid colission.... then it do not advance and remains so near of the depth charge explosions, and take damage.

Tweaking the files i reach a level where it happens not often, where it is the exception but not the rule.

[Redwine]

BTW, I think the DC_X_H is the hedgehog, right?

tater
Right

Right... may be they are a remain or waste from SH III, but any way i include the tweaked files for them with the ame settings i had into SH III.

[Fincuan]

I wonder if we could add a collisionable node tothe DCs. Meaning that they would hit the hull and bounce off. They'd still detonate when they were supposed to, but imagine the feeling of being DCed, hearing "Splash! Splash! Splash!" then "boom. BOOM. Klunk, scape... BOOOM!"

hehehe

With the current collision sounds, that would of course go like this: "splash! splash! splash!" -> boom, boom, SCCREEEETTTCCCHHH SCCCRRAAATTCCCHHH! (imagine the rubber boat colliding with your sub) :up:

[hyperion2206]

I remember one incident were I was DCed by a minesweaper and I came to PD to kill him. Just as I reached PD the minesweaper dropped DCs but then he noticed that I was at PD and backed up. The end of the story: He'd blown his DC racks up, but was otherwise undamaged.:doh:

[tater]

Sounds like the depth precision should be set to be fairly accurate. The detonation depth doesn't seem to do anything that I can tell.

It's odd, the hedgehog has the depth set to 2500 and the precision to 300. Their area of influence is ~2m, do they blow on contact? If that was the case, then the super deep detonation depth would be to give them time to physically hit a target. Odd that the depth value has no effect though. I set it to 1m, and they dropped fine. I set it to 30 (precision 1m), and they blow at various depths.

I have tried the radius dropped to 8m, and they can DC you for ages and not damage you---at least not enough to get the crew to say we're taking damage.

That might give the desired effect of being held down, and attacked with many DCs, but still surviving (which seems accurate to what US subs experienced in the PTO.

tater

[Redwine]

I have tried the radius dropped to 8m, and they can DC you for ages and not damage you---at least not enough to get the crew to say we're taking damage.

Mmmh... there is some thing strange with your files Tater... i use min=4m and max=10m into Die Slowly (wich is much more hard than in real life) and it works fine, you can be killed with no problems....

That might give the desired effect of being held down, and attacked with many DCs, but still surviving (which seems accurate to what US subs experienced in the PTO.

tater

That is what i was looking for and may be i reached ( i think so, always is matter of personale preferences) into Die Slowly.

Die Slowly not only tweaks the ships files, it tweaks the sub files too, giving you a long way to be killed, some times it takes a lot.

What i was looking to reach, was a real survival probability, it is about 87% of probability to survive a campaign along all the war...

Not real values or settings.

Sadly this makes to loss some game interesting, the life was much more easy to USA sub crew members than for germans... then in later versions i was looking for to make the sub more weak and pasible to be killed more easy.

The real matter is, if you do not make any stupid thing, you must to be enough safe... an american sub, running depth, under the thermal layer, and at silent running speed and condition, was not easy to detect and to kill... i remember i readed in some place, a web page from some historical place of the navy, a sub at silent runing can be detected by a jap pasive sonar only when was between 50m, it is about 165 feet.

Of course if you have the bad luck to be pinged, it is useless because you will be detected by the active sonar at a kilometer away or much more.

Check PM....

[Redwine]

I forget....

One thing i tryied was to replace the drop rack at back of the DDs, and change it by a K-Gun... works, but... not real, and the DDs was not able to aim well with this change, they droops the charges far from the sub.

[tater]

I added a few realistic DC throwers (after a certain date) to some IJN DDs using the P nodes. They are around here someplace...

[tater]

I think that depth precision is NOT what I had thought.

Some had suggested that setting a wide depth precision meant a wide ERROR.

Ie: the ASW asset would detect you at 25m. It aims for 25m, and if the precision is set to 15, it would be 25m +-15m, or a range of 10 to 40m.

I think that precision is the fidelity with which the DC can be aimed in the first place.

Ie: ASW asset detects you at 25m. The precision is set to 15, they aim the ashcans at 15m, or 30m to hit you.

If this is true, this is good since early IJN DCs had 30m settings. Later versions (the Type 2) had ~7.6m settings (~25 ft increments).

Now to find out if the detonation depth is a max depth.

tater

[tater]

Well, I had done a set of tests, and it was starting to appear the previous post was correct. I reloaded with some mission changes, and the escorts are blowing their butts up again.

Wonder if it's a weird interaction between the det depth setting, and precision.

Meaning that if the det depth were set to 60, and the precision 30, it might try and blow some at 0 depth. Maybe if the det depth isn't evenly divisible by the precision...

[tater]

A brief update on messing with DCs of various types (all at once, BTW ;) )

First, a dev post:

Asking an easy to answer question sure quiets things up, don't it ;)

tater
Tater, you know better than this :P Let us sleep during the night, at least when we're not pushing for release day.

I had a quick look in the code (mind you, I'm just a bystander with code, being a designer, and this design predates my arrival in sh3).

fall speed = drop rate in meters per second I assume. CORRECT

Detonate_depth = the default depth at which the DC will detonate. This is normally overwritten by the AI to the player's perceived depth (err, exact depth).

Depth_precision= the detonate depth value is altered by a random value between + depth precision and - depth precision.

There are some other factors involved, but basically there you have it.


So there is no way to set a max depth, or even a typical depth. There is no way to set DCs to only blow up at specific depths (only at either 30, 60, or 90m, for example instead of them aiming to detonate at 46.75m like they do).

I tried lower AI skill levels, no dice. We are stuck with DCs that go to any depth, and have no limitations on how fine the depth control is.


ASW ships blowing their asses off:

If you are at PD (~-15m to keel) they aim for that. If the precision is set to any number large enough to be meaningful, they might blow their own sterns off since they could aim at -10, and with +-5m slop, it goes off at 5m and boom. Stock DCs have a radius of 40m, so even at depth, they can damage the dropping ship. Decreasing the explosion radius helps though. I have experimented with a variant DC that works for slower ASW ships. It has a very slow fall rate, and I dropped the effective radius. (in RL they had a Type 95 version with a "parachute" to slow the fall through the water for exactly this purpose, small, slow subchasers). I gave it a high precision, so even dropped shallow, it should explode deep enough not to damage the stern.

OK, here is a basic issue that shows how it's hard to change just one thing (Redwine understands this all too well).

The subs have HUGE hitpoint values. S-18/S-42 have 500, Gar/Gato/Balao have 600, all the others have 320. A Takao CA has 500. Kongo has 800.

The DCs are tuned to damage submarines. But since they have huge hitpoints, the damage done by the DCs is also huge. If a direct DC hit can sink a sub, it can sink a Cruiser. I fear a really definitive fix would require changing all the hitpoints around. I need to retest with NSM on, perhaps NSM improves things a little. At least they won't be sunk out of hand, perhaps.

tater

[tater]

This post will be somewhat theoretical.

I'm gonna use the Trigger Maru sensor settings for this discussion as a baseline, because I think the stock ones are too easy...

One thing that is basic to TM, is the difficulty. TM is pretty hard compared to stock. The escorts come after you, and they will hold you down for ages if they don't kill you outright. The sensors are pretty effective.

Ducimus gave some pointers on how to tone down the AI via toning down the sensors, etc (the only AI control we have). Even so, because of the way DC attacks, etc are conducted, the AI really isn't too good at detecting you, IMO, just too good at prosecuting you.

He'd already thought about a lot of this, because the DCs have a much smaller blast radius than the stock 40m (which is realistic since in RL it was under 8m or so for pretty decent DCs). This allows you to get DCed for a long time with the better escorts without instantly getting killed.

One other thing (in the stock game) is that IJN ASW capability doesn't really improve that much over time, except in sensors.

That's the back story.

So I'm experimenting with DCs. My goal will be to have more than 1 type, in fact many different types. In RL, there were 2 basic IJN DCs, but there were variants within the 2 types. 3-4 different type 95s, all with 100kg warheads---the early Type 95 (60m max depth) and later Type 95 (90m max depth). They also had a version with a "parachute" that slowed the DC in the water (rolled off a boat/ship) so the little boat could get away in time. They then had 3 different Type 2s, a 105kg warhead, a 110kg warhead, and a 162kg warhead.

The depths are out of our control, sadly (posted above). The sim stuff for them doesn't really work.

We can mess with warheads, but of the 4 warhead strengths, 3 are virtually identical.

Now what?

Say we make a few new DC racks with new DCs. Some type 95s @ ~100kg warhead and 1.9 m/s fall speed (slower than the stock 3m/s). A Type 2 with a 110kg bomb, and another at 162kg. Both with 3m/s speeds. The stock DC is then in effect one of the 162kg type 2s.

Stock SH4 DC racks hold more DCs EACH than RL DDs carried usually, even later in the war.

Early in the war, the fleet DDs frequently carried no, or very few DCs at all.

I was thinking of testing more historical loads for DDs. I don't wanna go too far the other way, but the idea would be to reduce the DC loads by making alternat DC racks. Early racks might have 6-9 DCs. Later racks might have 18 since most sources quote 36 DCs for IJN DDs, and most have 2 roll racks. Using eqp loadouts, I can even then make alternate versions of the same ship. Default might be 36 so it will work in the stock game, but in a redone campaign, I could pick variable loads ofr each DD. It would keep you guessing, but you wouldn't have to evade 80 DCs per DD to escape, it might only take evading 18.

As the war progresses, they started holding more DCs, so you'd see ASW capability increase.

tater

[tater]

Well, even if I'll never get them to act like real IJN DCs, this is promising.

Makes evasion more possible if you only need to avoid 3 dozen DCs vs 7 dozen.

I even tried some of the small craft DCs I messed with, and got no blown up trawlers.

Such a mod would really make you appreciate that Kaibokans later in the war carried 120 DCs instead of the 12-18 they started the war with.

tater

[tater]

Interesting web site:

http://www.eugeneleeslover.com/USNAVY/CHAPTER-14-B.html

The effective radius of the percussive wave depends upon the structural strength of the attacked vessel, and no definite values can be stated. Approximate information indicates that a 600-pound charge may cause moderate damage at 80 feet, but to be fatal it must explode within about 30 feet. The 300-pound charge may prove fatal within 20 feet. It is to be noted that doubling the weight of charge does not double the effective radius.
The larger IJN Type 2 was 162kg warhead (356.4 lbs).

The above quote says the DC is lethal at ~20' (6.1m). It also says moderate damage on a much bigger warhead (600lbs) out to 80' (24m). The stock 40m is clearly too far, but it's not as far off as I had imagined. Of course I bet the damage as a function of distance is non-linear in RL. No idea if the game treats it as a linear gradient.

At the min SH4 explosion radius, 100% damage is applied, and to hitpoints as well I believe. So the stock setting of ~4m is not too bad, really. Setting the max radius too low (as I have been testing) is probably too far in the other directions. Looks like the TM value is pretty reasonable.

A quote about British air dropped depth bombs:
In the spring of 1942, a 250-pound depth charge increased effectiveness by 40%. The lethal range to penetrate a U-Boat was an explosion within about nineteen feet (5.8m—tater) of the U-boat.
Another quote I saw says 40 feet.

Another:
At the depth charge's minimum depth setting of 30 feet, the boats had to travel top speed to avoid damage from the blast. They also had to be dropped at least 50 feet apart to avoid setting each other off. The depth charges were only mounted when on patrol. No sense in having a 300lb target of high explosive on deck if not needed. Depending on the area of operation and main targets, many images of PT boats in action show that the racks were commonly removed. Mainly used against submarines, depth charges had to explode fairly close to the sub to be effective. This called for great expertise since, unlike ships and airplanes, the target was unseen (except for slight traces if you were lucky) and the depth vector also had to be considered. It was almost like firing the 20mm at a Zero at night during a lightning storm with bullets that only worked if you had set the right distance to the target. Here is the Navy's estimate of distance from the sub's hull / damage for this type of depth charge:

150-90 feet / Negligible
90-50 feet / Perhaps some (15m to 27m)
50-30 feet / Moderate (9m to 15m)
30-10 feet / Probably fatal (3m to 9m)


"Probably fatal" has a number of possibilities. I'd err on the side of survivability for our subs, but depth would be pretty critical. A DC in SH4 that happens to do 200+ damage to a sub, might not sink it outright, but the crush depth change could very well precipitate a total loss in a very short period of time.

tater

[Ducimus]

I've explained what the values do on other posts, so i wont get into that, ill just get into problems with design and intent when adjusting the variables.

By default the AI is really accurate with its depth charges, which are really large in radius. The large radius is nice, ONLY in that you'll get more equipment damage, which makes you "fight for the boat" . A DCing wihout malfunctions can get dull. The problem is the AI is pin point accurate 90% of the time with a 5 meter margine for error.

To make an encounter surviveable, you have a combination of 3 options.
1.) lower the blast radius. (problem is if you lower it to much, DC's become a joke. Nothing short of [direct contact when it explodes will cause damage, meanwhile DCs explode right next to subs, the realization that danger is nearly non existant sets in, and you as the modder get flak for it )

2.) increase the margine for error when the DC explodes. Problem is, tin cans will blow their own ass off when they set their DC's at a shallow depth

3.) lower the meter per second drop rate on the DC's, making them sink slower. A slow sink gives the player more time to manuver. Problem where is if you set it too slow, all you have to do is crawl at 2 kts at an extreme depth, and go afk, - the game will almost always miss.


Explosion depth does NOT work on DC's because the games AI actually sets the explosion depth itself, based on its sensor findings. If it thinks your at 115 meters, it will set the DC's at 115 meters, depth accuracy takes over from this point.

Explosion depth DOES work on hedge hogs. If you set it at 100 meters, with a 0 depth accuracy, the whole salvo will explode at 100 meters. Likewise, set the accuracy for 40 meters, and they'll explode randomly + or - 40 meters from the 100 meter mark.

[tater]

So what makes a hedgehog a hedgehog then? The DC_H_H files have the depth set at 2500 and the error 300.

Wonder if I can point a new DC roll rack at a clone of hedgehog ammo, set the depth to 45+-15 and I'd have very early war historical charges after a fashion. The trick to such a method (and the later chanrges with a 90m setting) would be to make MANY different racks, all set slightly different, and a few to the stock types as well (where they go to aim depth). Using ship loadouts, you could have Minekazes with as many different combos as you can make. Most might be like RL where you get deeper than 200ft and you are golden, but you never know...

tater

[tater]

1.) lower the blast radius. (problem is if you lower it to much, DC's become a joke. Nothing short of [direct contact when it explodes will cause damage, meanwhile DCs explode right next to subs, the realization that danger is nearly non existant sets in, and you as the modder get flak for it )

Yeah, I've discovered this. Your value is actually pretty good. A sub-choice would be to lower the damage done, but from what I've read a hit within a few meters should be pretty close to a 100% kill so there is a minimum you can go there, too.

2.) increase the margine for error when the DC explodes. Problem is, tin cans will blow their own ass off when they set their DC's at a shallow depth
The stock uses 5m, much more that that has serious issues, sadly.

3.) lower the meter per second drop rate on the DC's, making them sink slower. A slow sink gives the player more time to manuver. Problem where is if you set it too slow, all you have to do is crawl at 2 kts at an extreme depth, and go afk, - the game will almost always miss.
Stock is 3m/s, which is what the real Type 2 was. The earlier type 95s were 1.9m/s. I have also tested a VERY slow DC. In RL they put a chute on them so they could drop from small craft. I'm still gonna do this, actually, but they will be on the kind of boats that will be dropping on you in water so shallow that PD is about all you have. :)


Explosion depth does NOT work on DC's because the games AI actually sets the explosion depth itself, based on its sensor findings. If it thinks your at 115 meters, it will set the DC's at 115 meters, depth accuracy takes over from this point.

Explosion depth DOES work on hedge hogs. If you set it at 100 meters, with a 0 depth accuracy, the whole salvo will explode at 100 meters. Likewise, set the accuracy for 40 meters, and they'll explode randomly + or - 40 meters from the 100 meter mark.

Very interesting...

[Ducimus]

RE hedgehogs vs depth charges.


The big difference is that hedge hogs are not set to explode at a depth specified by the AI. Depthcharges however are.

See, if the AI decides it knows where you are, with a hedge hog, it just throws the salvo, and down they go until they hit something, or reach their explosion depth. Why this explosion depth exists, at all i don't know, they should go right down to the bottom, and in actutal play they do (sorta).

With depth charges, again, it sets a depth, and then it dumps them. Ive tried adjusting explosion depth on DC's in the past, and i never got any results, the AI seems to override whatever you set it at. Another thing to realize, is that the game is seemingly hardcoded with depth charge behavior. For example, depth charges will disappear at the 300 meter line. Likewise player subs i think poof at around 500 meters. Now i have tried to get DC's to explode deeper then 300 meters, but it just wont happen. Likewise, you can't force them to explode any shallower.

Hedge hogs, you can. In SH3, i modded them to detonate at 250 meters with a 40 or 50 meter depth accuracy. Of course, then being the masochist i am, i then modded them to behave with the range of a smaller depth charge. Historically inaccruate, but damn fun and scary too. hearing one of those salvos explode, it was massive, and the depth accuracy, always gave a chance that even at 278 meters, one still had a chance to make a contact hit on you.

[tater]

What I was thinking was making a regular DC, but have the game think it was a hedgehog so I could control the depth.


tater

[Ducimus]

ive thought of that in the past as well. Im just not sure how to go about it. I think your off into the happy land of hex editing. I know in the past ive tried very simple things like swapping the hedge hog file and renaming it the depth charge file. Hoping the game would read the dc file, but the projectile function like a hedge hog. Naturally that didnt work, nor did i really expect it to.

[tater]

Anyone know why the AI allows merchants to fire deck guns and AA at your sub, but they will not drop DCs?

In RL, merchants rolled a few DCs when an attack happened---not aimed. They also got DC mortars with a pretty substantial range sometimes. I was interested in at least adding roll racks to a few, but I want them to use them without being forced to act as escorts. The same solution would apply to Cruisers as well, even BBs with DCs. (IJN CAs sometimes had DCs, and Musashi had roll racks added to the fantail as well.

tater

[sergbuto]

Anyone know why the AI allows merchants to fire deck guns and AA at your sub, but they will not drop DCs?
Only units of Type=0 to 4 are able to drop DCs, at least that's how it was in SH3.

[tater]

Yeah, I know only 0-4 will drop them. I'm wondering if it's the ammo type that determines this, or something else...

I was wondering why because I thought perhaps we could trick them to fire DCs some how.

For example, if you had a gun that fired a DC instead of a shell the AI might think it's shooting a shell, and fire a DC instead.

Even a signal lamp that might actually drop a DC would be cool (very low ROF). That would simulate japanese merchants dumping a couple DCs off the stern when attacked to try and spook a sub... Hmmm.

tater

[sergbuto]

If I remember correctly (extensive testing I did was quite some time ago and for SH3) only an ammunition with the shell.dat, shell.sim structure/definitions/settings can be used for guns with possible lowest speed of about 200 m/s otherwise guns will not fire.

[tater]

Ah, I see. Was worth a shot thinking outside the box.

tater

[sergbuto]

Sure, it is worth. There is always a possibilty that I am wrong.

[Sailor Steve]

I hadn't looked at this thread in a while, and today I noticed this quote:
At the depth charge's minimum depth setting of 30 feet, the boats had to travel top speed to avoid damage from the blast.
It may mean nothing, but to add to that quote Tameichi Hara's book Japanese Destroyer Captain mentions that after taking a last contact reading they would accelerate to flank speed to avoid damage. This was done no matter what the depth setting. I don't know if the game can allow for something like this, but I'm pretty sure it would affect accuracy as well.

[tater]

That quote was from a PT boat. IJN DCs had a most shallow setting of 30m as far as I know (the type 2 DCs might have been ~7.5m, they seem to have had ~25' setting ticks)

There is no way to control the AI in that way, however.

[GerritJ9]

The Hedgehog was a contact weapon, i.e. IRL it had to actually hit something to explode- preferably an enemy sub. I think dr. Ballard wrote in his book about the "Lusitania" that the wreck site was littered with unexploded Hedgehogs, but I'd have to check as it's been some time since I last read the book. Apparently U-Boote used the wreck site as a hiding place when trying to evade Allied attacks.

[tater]

So I've done some testing with a new version of my DC mod with the 162kg versioned upped to nearly double stock DC damage. The min radius tuned to 6m, the max to 16m.

They still don't do damage as I'd expect.

Wonder what's going on.

[I-25]

I read about the happening somewhere can't remember where though, the crew could hear the DCs rolling down the side of the conning tower! I also recall an instance where a sub or U boat surfaced and had a dud DC caught on the deck casing! How about opening the hatch and seeing that little baby sitting there?! :o This happened to the I-176 North of Rabaul in 1943 after dropping off supples and evacuating wounded solders from finchaven. The XO said that one night a B-25 suddenly came out of the sky and they crashed dive under a hail of 50 cal. fire at about 20M down they heard a thump and a small boom like a firecracker. they came back up after a few hours and as they opened the hatch in the tower the first guy out must of freaked out. the charge was laying inside the tower bridge. they say some sort of yellowish substance was around it. the detonator had gone off but it didn't set off the main charge. Lucky Lucky japs!. On that same mission while at finchaven they got bombed by more B-25's while in the bay at night, the Capitan got shot (not mortally). and the XO beached the sub on a reef. after plugging up all the holes over night they waited for high tide to get the sub back off, high tide came and the sub wouldn't budge. then came the order from the bridge "all hands on deck". from atop the tower the XO ordered with a megaphone "Ok now, everybody run from one side of the boat to the other" and by god knows how Japanese ingenuity worked and the boat started rocking and they got it off!

[tater]

I just read Japanese Destroyer Captain: Pearl Harbor, Guadalcanal, Midway - The Great Naval Battles As Seen Through Japanese Eyes.

http://ecx.images-amazon.com/images/I/51%2B58Oe%2BriL._SL500_AA240_.jpg

Anyway, he mentions dropping charges (early in the war) set to 50m. Totally different than the only other info I had from navweaps.

Hmmm.

[DrBeast]

As expected, tater...there's always three sides to every story ;)

[tater]

Good book, BTW.

[Ducimus]

I wonder if....

one took a hedge hog, gave it the DC rack model, and then if possible, fixed it so only 1 hedge hog (also being changed to use the DC barrel model) was launched per attack, and then used that as a substitue for the depth charge rack.

IF that would work, you could force it to explode at a set depth. I have my doubts, but its an idea worth a try.

[Nisgeis]

Good book, BTW.

I'm reading that one now.

In 'War in the boats' by Captain William J. Ruhe, there is the following passage:

Levelled off at 350 feet, the Crevalle then caught another string of depth charges. They exploded almost as close as the previous string of charges, but a little more above the hull. I noted that the explosions indicated that the Japanese were now using a one-hundred-meter-depth setting on the charges. The prior charges had exploded at close overhead as the Crevalle passed 170 feet, indicating that the first string were set at fifty meters. The Crevalle was thus operated at 400-foot-depth so as to straddle the charges with their 50, 100, and 150 meter depth settings.

He mentions the 150 meter depth settings a couple of times.

I've also read in at least one patrol report (can't remember which one, Pampanito?) estimates of depth charges exploding below them at about 425 feet.

[tater]

The later type 2 had more settings. The Type 95 was supposedly 30, 60, and later 90m.

Given that they were on the receiving end, any guesses as to the depth setting were guesses, though.

War in the Boats is great, too.

[Nisgeis]

The later type 2 had more settings. The Type 95 was supposedly 30, 60, and later 90m.

Hmmm, what source are you getting your info from? Would be inetersting to read it. I've spent a while doing some research on this and the following is what I have come up with and it seems to support your info and mine. The Type 95 setting for 90m seems to have been a stop gap measure, early on it only had 30m and 60m settings.

War Damage Report No. 58, which details damage sustained by submarines during World War Two, covers all types of damage sustained by submarines, including collision, gunfire, mine, torpedo etcetera. It's located here:

http://ibiblio.net/hyperwar/USN/rep/WDR/WDR58/WDR58-1.html

In that it references 'Handbook of Japanese Explosive Ordnance, OpNav 30-3M of 15 August 1945 and Bureau of Ordnance Pamphlet 1507 of 20 April 1945' and says the following:

3-10. The pistols for both the Type 95 and type 2 depth charges were also almost exact copies of early British models and both operated on the same depth setting and firing principle, although they were not interchangeable between the two types of charges.12 (http://ibiblio.net/hyperwar/USN/rep/WDR/WDR58/WDR58-3.html#fn12) The firing mechanism of both pistols was actuated by the hydrostatic pressure of sea water flowing through a small orifice and slowly filling up an inner cylinder. Depth setting was accomplished by varying the size of the water inlet, thus determining the amount of time required to fill the inner cylinder. The smaller the inlet, the deeper the setting. The Type 95 depth charge pistol used early in the war could be set for operation only at depths of 98 feet, 98 feet with parachute, 197 feet, and "Safe". Later modification of this pistol provided for an additional setting of 292 feet. The maximum range of depth settings for the Type 2 depth charge pistol was much greater, a choice being available of 98 feet, 197 feet, 292 feet, 390 feet, 480 feet,and "Safe". It was apparently not possible with either type pistol to choose depth settings other than those enumerated above,even though detonation at some intermediate depth might be considered desirable.

3-11. No data are available as to how much variation could normally be expected between the prescribed depth settings on the pistols and the depths at which charge detonation would actually occur. The amount of error would naturally be affected by variations in sinking rates due to the following factors: (a) the method of launching, i.e., whether the charges were projected from throwers or dropped from stern racks; and (b) by the condition of the sea, i.e., whether still or disturbed. The accuracy with which the orifices in the pistols were initially machined would also affect the detonation depth. Tests conducted by the British on their early pistols indicated that discrepancies of as much as 60 feet should be expected for charges set for detonation at 250 foot depth. It should be noted that even though a Japanese depth charge were to come to rest in water more shallow than that for which its pistol had been set, it would still fire when sufficient water had seeped through the entry orifice to provide the minimum pressure required. This is believed to account for many of the delayed depth charge detonations which have been reported by U.S. submarines.

Although the Type 2 charge could be set to 480 feet, it seems that the maximum setting normally used was 390 feet. This is also corroborated by the 'REPORTS OF THE U. S. NAVAL TECHNICAL MISSION TO JAPAN', which can be found here:

http://www.fischer-tropsch.org/primary_documents/gvt_reports/USNAVY/USNTMJ%20Reports/USNTMJ_toc.htm

The report entitled 'Japanese Anti-Submarine Warefare' slightly contradicts the above report and says that a depth charge pattern for both coastal defence and destroyers contained a mix of depth settings of 30m, 60m, 90 and 120m. It says:

'The Japanese had no means of determining the depth of enemy submarines, and their depth charge patterns were designed to cover all depths within the limitations of the depth settings on their charges.'

The contradictory part is:

Maximum depth setting of charges usually carried was 120 meters and a proportionate number of charges with this setting was included in each pattern.

That disagrees with the maximum depth setting of 480 feet on the Type 2, but it cannot be a Type 95 as that only went to 90m. It then goes on to say:

"Q" deep-setting pistol for depth charges had been developed, but, apparently, issue to ships had not become general and no specific doctrine for its use had been developed. Inasmuch (sic) as deep-setting pistols had been designed it is possible that the Japanese were working on the idea of special procedure for this type of attack.

I cannot find any other reference to a "Q" pistol, but there is a refence in the report 'Japanese Depth Charges', to a Type 3. 'Japanese Depth Charges' opening states:

'The purpose of this report is to provide information about the Japanese depth charges, namely influence and standard depth charge pistols. Interrogation has revealed that onlt two influence depth charges were under consideration, and of these, only one was approaching finality of design. Drawings supplied by the Japanese of depth charge pistols are included.'

The report describes the two influence depth charges as magnetic influence (Type 4, part tested but never used operationally) and Accoustic Depth Charge (no designation, presumably as none had been built). The magnetic influence depth charge was set to detonate when in proximity or if nothing triggered it, it was set to explode at 656 feet (200m).

It then details the type 3 model 1 pistol, which is similar to the type 2 pistol, but extra time required for reaching the greater depth is provided by a delay train which is initiated by the firing pin (hydrostatic). Depth settings for the Type 3 Model 2 depth charges are at 131.2 feet (40m), 262.4 feet (80m), 393.6 feet (120m), 524.8 feet (160m) and 656 feet (200m). It doesn't say specifically, but it doesn't look as though the type 3 pistol would fit in the type 2 depth charge, so I don't think it would be retrofitted. Perhaps this type 3 is the afforementioned "Q" type?


Given that they were on the receiving end, any guesses as to the depth setting were guesses, though.

Well, that is certainly true for far depth charges, but for close and very close depth charges, where you get a shock wave, I think you'd be able to tell which direction it came from. Certainly close depth charges would move the boat and it was established that depth charges close underneath your boat would also cause you to rise and likewise depth charges close above would force you down. I don't think they had a problem knowing where the depth charges were exploding, not that it helped them. The DCDI was developed primarily so captains could get an understanding of where depth charges were exploding when they were not close, so they could determine where the Japanese thought they were and maneuver accordingly. There are however two accounts mentioned, in WDR 58, the first of the USS Seahorse 4th July 1944, during the fifth patrol of of depth charges being dropped and at a depth of 470 feet, the DCDI indicated that the depth charges were exploding below her. USS Threadfin reported that whilst being depth charged on 28 March 1945, during her second patrol, over half the detonations occurred at depths greater than 450 feet as indicated by the DCDI.


War in the Boats is great, too.

It certainly is. Unfortunately for me, most of the submarine books are only available in the U.S. and not where I am :shifty: .

Anyway, hope this helps the discussion of depth charges, there is also discussion of air dropped depth charges in WDR 58.

Edit: Stocks of Type 95s seem to have been used up by mid 1943, their use overlapping the Type 2s

[Ducimus]

The previous idea i posted, and several different variations of similiar ideas didn't work.

About the most i accomplished was getting a depth charge rack, to eject hedge hog salvos at the same rate it drops depth charges. Seeing a stack of 4 rings worth of hedge hogs on their way down, was halarious. Id have taken a screenshot and posted it in the "modding bloopers" thread if screens did it any justice. It was just something you had to see for yourself, it was halarious.

[tater]

When I have time to get back into the swing of things, I am going to reevaluate the possibility of launching air-dropped DCs from ships so I can force the 30/60/90m values.

The navweaps.com website claims the type 2 had 7.5m settings, but I think your source sounds better by far. Awesome info.

tater

[Ducimus]

When I have time to get back into the swing of things, I am going to reevaluate the possibility of launching air-dropped DCs from ships so I can force the 30/60/90m values.


I tried something similar to that last night. I used the airbomb controller inplace of the DC controller inside the DC files. This also was funny to watch. The DC's would just lay there motionless, frozen in place about 5 feet above the water.

[tater]

That's exactly what mine did a few months ago.

[Ducimus]

Well im stumped on it honestly. If theres a way to trick it i can't find it right now. Seems to me were all trying similar things. Personally im gonna toss this onto the pile of things i failed at. Forcing DC explosions at a given depth has been a problem since the earliest days of SH3. I think this is one of those things where, if it was possible, someone would have done it by now.

[tater]

bump for my future reference. :D

[W_clear]

I think the adjustment of Depth Charge values of the parameters, it is wrong to choose.SH4 original Depth Charge values are realistic. if you want to weaken Depth Charge values for ordinary players, that is right!
If you want to strengthen the Depth Charge values, it is wrong. Should be used to improve Destroyer's ability to replace.

[tater]

Well, in my mod I used the stock SH4 DC to represent the larger of the IJN charges and the new ones are earlier, smaller models.

I did also reduce the damage radius. 40m is far, far too large to do any damage.

Also, the stock game has grossly too many DCs per ship. 40 per rack.